Pressure sensor

Abstract

To simultaneously achieve pressure resistance and moisture resistance in a structure for fixing a pressure guide tube to a sensor package.SOLUTION: A pressure sensor 10 includes a sensor device 20 for detecting the pressure of a fluid, a pressure guide pipe 40A and 40B for guiding the pressure of the fluid to the sensor device 20, and a sensor package 30 for housing the sensor device 20, the sensor package 30 having a through hole 31A and 31B through which the pressure guide pipe 40A and 40B pass. The pressure sensor 10 is provided with resin-made adhesive 40A and 40B for adhering the connecting pipe 31A and 31B to the sensor package 30 in a state of blocking each clearance between the connecting pipe 40A and 40B and the through-hole 51A and 51B, and moisture-proof agent 51A and for covering the adhesive and. 51B 52A 52B.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a pressure sensor. [Background technology]

[0002] Patent Document 1 discloses a pressure sensor including a sensor element that detects fluid pressure, a pressure guiding tube that guides the fluid pressure to the sensor element, and a sensor package that houses the sensor element and has a through-hole through which the pressure guiding tube passes. In this pressure sensor, the pressure guiding tube is gold-plated, and the gold-plated portion is soldered to fix the pressure guiding tube to the sensor package. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-99902 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned gold-plated soldering ensures moisture protection for the inside of the sensor package, but has the problem of relatively low pressure resistance.

[0005] An object of the present invention is to simultaneously realize pressure resistance and moisture resistance in a structure for fixing a pressure guiding tube to a sensor package. [Means for solving the problem]

[0006] The pressure sensor according to the present invention comprises a sensor element that detects the pressure of a fluid, a pressure guiding tube that introduces the pressure of the fluid to the sensor element, a sensor package that houses the sensor element and has a through hole through which the pressure guiding tube passes, a first adhesive made of resin that adheres the pressure guiding tube to the sensor package while sealing the gap between the pressure guiding tube and the through hole, and a moisture-proof agent that covers the first adhesive. [Effects of the Invention]

[0007] According to the present invention, pressure resistance and moisture resistance are simultaneously achieved in the structure for fixing the pressure guiding tube to the sensor package. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a pressure sensor according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of the pressure sensor of FIG. [Figure 3] FIG. 3 is an enlarged cross-sectional view of a part of FIG. [Figure 4] FIG. 4 is a cross-sectional view according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a pressure sensor according to an embodiment of the present invention will be described with reference to the drawings. Note that the up and down directions set in the drawings are set for convenience and do not limit the actual installation direction of the pressure sensor.

[0010] 1 to 3, a pressure sensor 10 according to this embodiment is configured to be used in a pressure measurement device (for example, the pressure measurement device described in Patent Document 1) that measures the differential pressure of a fluid to be measured. The pressure sensor 10 includes a sensor element 20 for detecting the differential pressure, a sensor package 30 that houses the sensor element 20 and is fixed to a circuit board of the pressure measurement device, and pressure guiding tubes 40A and 40B that are welded to the body of the pressure measurement device and that introduce low-pressure and high-pressure side pressures that constitute the differential pressure of the fluid to the sensor element 20. The pressure sensor 10 further includes adhesives 51A and 51B that bond and fix the pressure guiding tubes 40A and 40B to the sensor package 30, a moisture-proof agent 52A that covers the adhesives 51A and 51B, and adhesives 53A and 53B that bond and fix the pressure guiding tubes 40A and 40B to the sensor element 20, respectively.

[0011] The sensor element 20 includes an element body 21, holes 22A and 22B, pressure chambers 23A and 23B, diaphragms 24A and 24B, and an interlocking fluid 25. The element body 21 is a laminated body made of silicon and other elements. The holes 22A and 22B are provided in the element body 21, extend in the vertical direction, and open to the bottom surface of the element body 21. The pressure chambers 23A and 23B are provided in the element body 21 and are connected to the upper ends of the holes 22A and 22B, respectively. The diaphragms 24A and 24B are disposed in the element body 21 and face the pressure chambers 23A and 23B, respectively. The interlocking fluid 25 is filled in the element body 21 and interlocks the displacement of the diaphragms 24A and 24B.

[0012] Pressure guiding tubes 40A and 40B are inserted into holes 22A and 22B, respectively. Pressure guiding tube 40A introduces the pressure of the low-pressure side of the fluid to be measured into pressure chamber 23A connected to hole 22A. The pressure introduced into pressure chamber 23A is received by diaphragm 24A. Pressure guiding tube 40B introduces the pressure of the high-pressure side of the fluid to be measured into pressure chamber 23B connected to hole 22B. The pressure introduced into pressure chamber 23B is received by diaphragm 24B.

[0013] The sensor element 20 also includes a piezoelectric element that detects deformation of the diaphragms 24A and 24B due to the pressure they receive. The sensor element 20 converts the deformation into an electrical signal using the piezoelectric element or the like, and outputs the converted electrical signal to the circuit board outside the sensor package 30 via wiring (not shown) that passes through the sensor package 30.

[0014] The sensor package 30 is composed of a package body 31 formed in a box shape with an opening at the top, a square ring-shaped spacer 32 fixed to the upper end of the package body 31, and a lid 33 fixed to the spacer 32 and closing the package body 31. The package body 31 is made of a ceramic material, and the spacer 32 and the lid 33 are made of a ceramic material or a metal material. Through holes 31A and 31B are formed in the bottom of the package body 31, through which the pressure guiding tubes 40A and 40B pass, respectively.

[0015] Each of the pressure guiding tubes 40A and 40B is made of stainless steel and bent into a predetermined shape.

[0016] With its tip inserted into hole 22A of sensor element 20, pressure guiding tube 40A is adhered to sensor element 20 by adhesive 53A applied to hole 22A. Part of adhesive 53A penetrates into the gap between pressure guiding tube 40A and the inner surface of hole 22A, closing and sealing the gap.

[0017] With its tip inserted into hole 22B of sensor element 20, pressure guiding tube 40B is adhered to sensor element 20 by adhesive 53B applied to hole 22B. Part of adhesive 53B enters the gap between pressure guiding tube 40B and the inner surface of hole 22B, closing and sealing the gap.

[0018] The adhesives 53A and 53B are made of resin, for example, an epoxy adhesive, and harden in a downwardly bulging shape after application.

[0019] The interior of the sensor package 30 is kept in a vacuum state or filled with an inert gas such as N2 gas to prevent moisture penetration and / or moisture degradation of the resin-based (especially epoxy-based) adhesives 53A and 53B, i.e., moisture-proof. To maintain this state, the package body 31, spacer 32, and lid 33 are welded or brazed. Furthermore, adhesive 51A is applied to the through-hole 31A through which the pressure guiding tube 40A passes. A portion of the adhesive 51A penetrates into the gap between the pressure guiding tube 40A and the inner surface of the through-hole 31A, closing and sealing the gap. Furthermore, adhesive 51B is applied to the through-hole 31B through which the pressure guiding tube 40B passes. A portion of the adhesive 51B penetrates into the gap between the pressure guiding tube 40B and the inner surface of the through-hole 31B, closing and sealing the gap. The adhesives 51A and 51B are made of resin, particularly epoxy-based adhesives. The adhesives 51A and 51B can be made of the same material as the adhesives 53A and 53B. After application, the adhesives 53A and 53B harden in a downwardly bulging shape.

[0020] Conventionally, the bonded portions formed by adhesives 51A and 51B have been sealed by soldering. In such cases, the soldered portions between pressure guiding tubes 40A and 40B and sensor package 30 are gold-plated to ensure solder wettability. However, solder soldered to gold plating is inferior in pressure resistance (e.g., tensile strength) to solder soldered to the base material of pressure guiding tubes 40A and 40B. Therefore, in this embodiment, instead of soldering, an adhesive is applied between pressure guiding tubes 40A and 40B and sensor package 30, and the gaps are sealed by adhesives 51A and 51B. In this case, gold plating is not necessary because pressure resistance is higher without gold plating than with gold plating (see Table 1). [Table 1]

[0021] Although adhesives 51A and 51B ensure pressure resistance (epoxy adhesives, in particular, provide high adhesive strength), because adhesives 51A and 51B are made of resin, like adhesives 53A and 53B, adhesives 51A and 51B suffer from moisture-proofing issues, such as moisture (water vapor) penetration and / or moisture degradation, which result in poor long-term durability. Therefore, in this embodiment, adhesives 51A and 51B are covered with moisture-proofing agents 52A and 52B. This provides moisture protection for adhesives 51A and 51B, thereby preventing the occurrence of moisture penetration and / or moisture degradation problems in adhesives 51A and 51B. Moisture-proofing agents 52A and 52B may be made of a material that is impermeable or difficult to transmit moisture (i.e., a highly moisture-proof material, e.g., a material with lower moisture permeability than adhesives 51A and 51B), such as a moisture-proof coating agent such as varnish or a potting agent. Examples of materials for moisture-proof coating agents and potting agents include polyurethane and fluorine-based materials.

[0022] As described above, the pressure sensor 10 according to this embodiment includes the sensor element 20 that detects the pressure of a fluid, the pressure guiding tubes 40A and 40B that guide the fluid pressure to the sensor element 20, and the sensor package 30 that houses the sensor element 20 and has through holes 31A and 31B through which the pressure guiding tubes 40A and 40B pass. The pressure sensor 10 also includes resin adhesives 51A and 51B that bond the pressure guiding tubes 40A and 40B to the sensor package 30 while sealing the gaps between the pressure guiding tubes 40A and 40B and the through holes 31A and 31B, and moisture-proof agents 52A and 52B that cover the adhesives 51A and 51B, respectively. With this configuration, the combination of the adhesive 51A and the moisture-proof agent 52A and the combination of the adhesive 51B and the moisture-proof agent 52B simultaneously achieves pressure resistance and moisture-proofing.

[0023] In this embodiment, the pressure sensor 10 further includes resin adhesives 53A and 53B that secure the pressure guiding tubes 40A and 40B to the sensor element 20. The adhesives 51A and 51B and the adhesives 53A and 53B are formed of the same material. For example, if conventional solder were used instead of the adhesive 51A, the molten solder could pass through the through-hole 31A and come into contact with the adhesive 53A during soldering, potentially melting the adhesive 53A. To prevent this, it was necessary to limit the amount of adhesive 53A used and reduce the amount of adhesive 53A that would bulge. As described above, by using the same material for the adhesives 51A and 51B and the adhesives 53A and 53B, there is no problem even if the adhesives come into contact with each other, and there is no need to limit the amount of adhesive 53A and 53B used. This allows for the use of more adhesives 53A and 53B, improving adhesive strength.

[0024] 4, adhesives 51A and 51B may be formed so as to pass through through-holes 31A and 31B, respectively, and connect to adhesives 53A and 53B, respectively. By using the same material for adhesives 51A and 51B and adhesives 53A and 53B, there is no problem even if they come into contact with each other, so they may be connected to each other. In this case, the adhesive strength of each adhesive is improved, and a robust pressure sensor 10 is obtained.

[0025] The portions of pressure guiding tubes 40A and 40B to which adhesives 51A and 51B and adhesives 53A and 53B are respectively bonded are preferably not plated, which improves pressure resistance compared to the above-described plated portions.

[0026] The configurations disclosed in this specification, which are examples of the above-described embodiments and modifications, are described below. Note that the present invention is not limited to the following configurations. Only a part of the configurations in each of the supplementary notes may be added to other supplementary notes.

[0027] (Appendix 1) a sensor element for detecting the pressure of the fluid; a pressure guiding tube for guiding the pressure of the fluid to the sensor element; a sensor package that houses the sensor element and has a through hole through which the pressure guiding tube passes; a first adhesive made of resin that bonds the pressure guiding tube to the sensor package while sealing a gap between the pressure guiding tube and the through hole; a moisture-proofing agent covering the first adhesive; A pressure sensor comprising: (Appendix 2) a second adhesive made of resin that fixes the pressure guiding tube to the sensor element; The first adhesive and the second adhesive are made of the same material. 2. The pressure sensor of claim 1. (Appendix 3) The first adhesive passes through the through-hole and is connected to the second adhesive. 3. The pressure sensor according to claim 1 or 2. (Appendix 4) The portion of the pressure guiding tube to which the first adhesive is adhered is not plated. 4. The pressure sensor according to any one of Supplementary notes 1 to 3.

[0028] The present invention is not limited to the above-described embodiments and modifications, nor to the above-described supplementary notes. For example, the present invention includes various modifications to the above disclosure that are understandable to those skilled in the art within the scope of the technical concept of the present invention. For example, the present invention is applicable to various pressure sensors, and the number of pressure guiding tubes may be at least one. The pressure guiding tube may be configured, for example, so that the pressure of the fluid to be measured can be introduced into the sensor element. The configurations listed above may be combined as appropriate within a consistent range. Furthermore, any configuration may be deleted as appropriate. [Explanation of symbols]

[0029] 10...pressure sensor, 20...sensor element, 21...element body, 22A...hole, 22B...hole, 23A...pressure chamber, 23B...pressure chamber, 24A...diaphragm, 24B...diaphragm, 25...interlocking fluid, 30...sensor package, 31...package body, 31A...through hole, 31B...through hole, 32...spacer, 33...lid, 40A...pressure guiding tube, 40B...pressure guiding tube, 51A...adhesive, 51B...adhesive, 52A...moisture-proof agent, 52B...moisture-proof agent, 53A...adhesive, 53B...adhesive.

Claims

1. a sensor element for detecting the pressure of the fluid; a pressure guiding tube for guiding the pressure of the fluid to the sensor element; a sensor package that houses the sensor element and has a through hole through which the pressure guiding tube passes; a first adhesive made of resin that bonds the pressure guiding tube to the sensor package while sealing a gap between the pressure guiding tube and the through hole; a moisture-proofing agent covering the first adhesive; A pressure sensor comprising:

2. a second adhesive made of resin that fixes the pressure guiding tube to the sensor element; The first adhesive and the second adhesive are made of the same material. The pressure sensor according to claim 1 .

3. The first adhesive passes through the through-hole and is connected to the second adhesive. The pressure sensor according to claim 2 .

4. The portion of the pressure guiding tube to which the first adhesive is adhered is not plated. The pressure sensor according to claim 1 .

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